Liquid Electrolyte Composition Comprising a Salt, Electrochemical Cell Comprising the Electrolyte Composition, Salt, and Use of the Salt in the Electrochemical Cell

Abstract

Liquid electrolyte compositions comprising a salt of the formula (I) which has an anionic complex comprising three bidentate ligands are provided. The complex comprises phosphorus as the central ion. Electrochemical cells comprising the liquid electrolyte composition are further provided. Salts of formula (I) are further provided.

1 . A liquid electrolyte composition for an electrochemical cell, comprising:
 (A) sulfur dioxide; and   (B) at least one salt of formula (I)   
       
         
           
           
               
               
           
         
         wherein 
         M is a metal cation selected from the group consisting of alkali metals, alkaline earth metals, and metals of group 12 of the Periodic Table of the Elements; 
         m is 1 or 2; 
         and 
         L 1 , L 2 , and L 3  each independently represents a perfluorinated aliphatic or aromatic bridging radical, wherein the bridging radical forms a five- to eight-membered ring with the P and with two oxygen atoms bonded to the P and the bridging radical, and wherein the ring contains a chain of 2 to 5 carbon atoms optionally interrupted by an oxygen atom. 
       
     
     
         2 . The electrolyte composition according to  claim 1 , wherein the metal cation M is lithium. 
     
     
         3 . The electrolyte composition according to  claim 1 , wherein L 1 , L 2 , and/or L 3  each independently comprises a linear, branched, or cyclic saturated hydrocarbon chain. 
     
     
         4 . The electrolyte composition according to  claim 1 , wherein the ring contains an uninterrupted chain of 2 to 5 carbon atoms. 
     
     
         5 . The electrolyte composition according to  claim 1 , comprising at least one lithium salt of P(O 2 C 3 (CF 3 ) 6 ) 3  of formula (III) 
       
         
           
           
               
               
           
         
         P(O 2 C 2 (CF 3 ) 4 CF 2 ) 3  of formula (IV) 
       
       
         
           
           
               
               
           
         
         P(O 2 C 2 (CF 3 ) 4 ) 3  of formula (V) 
       
       
         
           
           
               
               
           
         
         or combinations thereof. 
       
     
     
         6 . The electrolyte composition according to  claim 1 , comprising the at least one salt in a concentration of 0.01 to 15 mol/L, based on the total volume of the electrolyte composition. 
     
     
         7 . The electrolyte composition according to  claim 1 , comprising at least one further additive in a proportion of 0-10%. by weight, based on the total weight of the electrolyte composition, wherein the further additive is selected from the group consisting of vinylene carbonate (VC), 4-fluoro-1,3-dioxolan-2-one (FEC), lithium fluoride, lithium hexafluorophosphate, cis-4,5-difluoro-1,3-dioxolan-2-one (cDFEC), 4-(trifluoromethyl)-1,3-dioxolan-2-one, lithium tris(perfluorethyl)trifluorophosphate, lithium tris(perfluoropropyl)trifluorophosphate, lithium tris(perfluorobutyl)trifluorophosphate, lithium tris(perfluoropentyl)trifluorophosphate, bis(trifluoromethanesulfonyl)imide (LiTFSI), bis(fluorosulfonyl)imide (LiFSI), isomers thereof, and combinations thereof. 
     
     
         8 . The liquid electrolyte composition according to  claim 1 , comprising:
 (A) sulfur dioxide;   (B) at least one salt of formula (I) in a concentration of 0.01-15 mol/L, based on the total volume of the electrolyte composition; and   (C) 0-10% by weight, based on the total weight of the electrolyte composition, of at least one additive selected from the group consisting of vinylene carbonate (VC), 4-fluoro-1,3-dioxolan-2-one (FEC), lithium fluoride, lithium hexafluorophosphate, cis-4,5-difluoro-1,3-dioxolan-2-one (cDFEC), 4-(trifluoromethyl)-1,3-dioxolan-2-one, lithium tris(perfluorethyl)trifluorophosphate, lithium tris(perfluoropropyl)trifluorophosphate, lithium tris(perfluorobutyl)trifluorophosphate, lithium tris(perfluoropentyl)trifluorophosphate, bis(trifluoromethanesulfonyl)imide (LiTFSI), and bis(fluorosulfonyl)imide (LiFSI), isomers thereof, and combinations thereof.   
     
     
         9 . An electrochemical cell comprising a cathode, an anode, and an electrolyte composition according to  claim 1  in contact with the cathode and the anode. 
     
     
         10 . The electrochemical cell according to  claim 9 , wherein the electrochemical cell is a lithium-ion cell, and wherein the electrolyte composition comprises:
 (A) sulfur dioxide;   (B) 0.5-2 mol/L of a salt of formula (I) based on the total volume of the electrolyte composition; and   (C) 0.1-2% by weight of lithium hexafluorophosphate and 0.1-2% by weight of 4-fluoro-1,3-dioxolan-2-one (FEC), based on the total weight of the electrolyte composition.   
     
     
         11 . A salt of formula (I) 
       
         
           
           
               
               
           
         
         wherein 
         M is a metal cation selected from the group consisting of alkali metals, alkaline earth metals, and metals of group 12 of the Periodic Table of the Elements; 
         m is 1 or 2; 
         and 
         L 1 , L 2 , and L 3  each independently represents a perfluorinated aliphatic or aromatic bridging radical, wherein the bridging radical forms a five- to eight-membered ring with the P and with two oxygen atoms bonded to the P and the bridging radical and wherein the ring contains a chain of 2 to 5 carbon atoms optionally interrupted by an oxygen atom. 
       
     
     
         12 . The salt according to  claim 11 , wherein the salt is lithium triperfluoropicanolatophospate (LiP(PFP) 3 ) of formula (V): 
       
         
           
           
               
               
           
         
       
     
     
         13 . An electrochemical cell comprising the salt according to  claim 11 . 
     
     
         14 . The electrochemical cell according to  claim 13 , wherein the salt is a lithium ion-conducting. 
     
     
         15 . The electrochemical cell according to  claim 13 , further comprising sulfur dioxide. 
     
     
         16 . The electrolyte composition according to  claim 1 , wherein the at least
 one salt of formula (I) comprises a salt of formula (II)   
       
         
           
           
               
               
           
         
         wherein each n is independently 0, 1, 2, or 3; 
         each R is independently C 1 -C 10 -alkyl, fluorine, or C 1 -C 10 -perfluoroalkyl; 
         M is a metal cation selected from the group consisting of alkali metals, alkaline earth metals, and metals of group 12 of the Periodic Table of the Elements; and 
         m is 1 or 2. 
       
     
     
         17 . The electrolyte composition according to  claim 16 , wherein each R is independently selected from the group consisting of trifluoromethyl, perfluoroethyl, perfluoropropyl, perfluoroisopropyl, perfluoro-n-butyl, perfluoro-sec-butyl, perfluoroisobutyl, and perfluoro-tert-butyl. 
     
     
         18 . The electrolyte composition according to  claim 1 , comprising the at least one salt in a concentration of 0.1 to 10 mol/L. 
     
     
         19 . The salt of formula (I) according to  claim 11 , comprising a salt of formula (II) 
       
         
           
           
               
               
           
         
         wherein each n is independently 0, 1, 2, or 3; 
         each R is independently C 1 -C 10 -alkyl, fluorine, or C 1 -C 10 -perfluoroalkyl; 
         M is a metal cation selected from the group consisting of alkali metals, alkaline earth metals, and metals of group 12 of the Periodic Table of the Elements; and 
         m is 1 or 2. 
       
     
     
         20 . The electrolyte composition of  claim 19 , wherein each R is independently selected from the group consisting of trifluoromethyl, perfluoroethyl, perfluoropropyl, perfluoroisopropyl, perfluoro-n-butyl, perfluoro-sec-butyl, perfluoroisobutyl, and perfluoro-tert-butyl.